Wildlife experts also say that the legal and illegal trade in hippo teeth needs to be closely monitored.
The common hippo is listed in Appendix II of CITES meaning that it could be threatened with extinction unless trade is closely controlled.
The 10 countries seeking a worldwide ban on trade note argue that there is strong evidence of the "co-mingling of legal and illegal hippo ivory", suggesting that poached ivory is "laundered into the legal market".
Without stronger controls, campaigners warn, hippos may share the fate of elephants, which have become endangered - or critically endangered in the case of the African forest elephant - because so many were killed by poachers for their tusks.
